The fastest land mammal in the world, the cheetah (Acinonyx jubatus) has many adaptations that allow it to sprint across the plains. Its rangy frame supports long limbs and a deep chest cavity, and this species has a small waist and an extremely flexible spine. Unlike other cats, the cheetah has claws that are not fully retractable, enabling it to grip the ground when in a hunting sprint. The large nostrils allow greater amounts of air to enter the lungs, and the tail is particularly long to provide extra balance when cornering.